What is Relay and GraphQL?

If you’re an application developer, there’s a strong chance that by now, you’ve probably heard quite a bit about Relay and Graph QL. Announced by the Facebook dev team in January of 2015, the pair were designed with an eye towards the issues often found in complex application development. But what are they, and where does the value lie for you? Read on as I explain all.

GraphQL is a data querying language designed to describe the increasingly complex nested data dependencies of modern applications. Facebook have been using it to build their native applications for some time now. On the server end, GraphQL is configured to map queries with underlying data fetching code.

Relay is a framework designed to provide data-fetching functionality for applications developed in the React framework (introduced in 2013, again, by Facebook). Each component specifies its own data dependencies declaratively using the aforementioned GraphQL, and the data is made available to the component via properties on this.props. Developers are encouraged to compose these React components naturally, and let Relay take care of composing the data queries into efficient batches. With this, Facebook say, Relay will provide each component with the data it requested and no more, as well as updating those components when the data changes and maintain a client side cache of all data.

So, where’s the value in Relay above other, similar frameworks? Well, the results can all be found in simplicity. With the sheer scale of Facebook’s mobile user base (1.44 billion as of April 2015), the ability to make correct, high performance applications in a straightforward and clear way is incredibly valuable. The design allows teams of any size to make changes with a high degree of isolation. By co-locating the queries with the view code, Relay lets develops reason about what a component is doing by looking at it in isolation, rather than in context of where it was rendered, unlike most frameworks. Relay also moves tricky things like fetching data, performance and changing data management to the framework to allow you to focus on building your app.

Of course, that’s just the start of the advantages that this pairing can offer an application developer. The framework has long since been made open source on GitHub, and I can’t begin to recommend it highly enough — it might just make those coding headaches disappear (maybe).